Non-invasive methods of treatment of, for example, intractable disease such as nerve damage include repetitive transcranial magnetic stimulation (rTMS). The repetitive transcranial magnetic stimulation is a method of treatment in which a symptom is ameliorated by giving a magnetic stimulation to a certain site (motor area) of the brain from the outside with a magnetic field generated by applying an electric current to a conductive coil brought closer to the head of a patient.
The repetitive transcranial magnetic stimulation requires the magnetic field allowed to act on the motor area of the brain corresponding to a disease. The coil is desirably disposed in as close contact as possible with the patient in terms of energy efficiency. For example, Patent Document 1 describes that a magnetic stimulation device used in the repetitive transcranial magnetic stimulation has a coil fixed to a shell like a cap or a helmet put on the head of a patient.
Because the coil generates heat due to energization and the magnetic stimulation device becomes hot when the device is continuously used, a patient may feel heat. Also, a patient may feel uncomfortably hot due to air heated by heat generation of the magnetic stimulation device and the patient may avoid the treatment.
To solve these problems, Patent Document 2 describes a method of cooling a coil by sending an air current in a direction so that the air current is not directly applied to a patient in a magnetic stimulation device fortreatment of urinary incontinence having a magnetic stimulation unit disposed in a seating part.
Patent Document 3 describes a position setting method and a cooling mode in a transcranial magnetic stimulation system including a helmet. This document describes several techniques with respect to how to release heat generated from a magnetic coil giving stimulation to a treatment part mostly on the head. Specifically, the techniques include a cooling mode utilizing the heat of vaporization of Freon gas, a water-cooling mode utilizing water stored in a separate unit, and an air-cooling mode utilizing air. Among these, the water-cooling and air-cooling modes are described as bringing a radiator system into contact with a coil to stabilize the temperature of the coil. However, the cooling mode using Freon gas is not appropriate from the viewpoint of environment pollution. The water-cooling mode may lead to a considerably large-scale device because of use of a tank. Moreover, the water-cooling and air-cooling modes using the radiator system lead to an increase in size of a coil unit and generate a pressure loss and noise in the radiator, and it is not practical to use an device having such problems near the head (near the ears) of a patient. As the device is used for a longer time, the radiator may deteriorate and cause liquid leakage and, therefore, the device has a safety problem in terms of using the device near the top of the head of a patient for a long period.
Patent Document 4 discloses a cooling technique in which a coil and a fan are arranged inside a housing including a patient interface plate in this order from the interface plate so that air sucked from an inlet in a housing rear portion separate from a patient is brought into contact with the interface plate and the coil in series based on the drive of the fan. However, since the inlet is formed in the vicinity of the outer circumference of the housing (on the outside of the fan) in this cooling technique, the air sucked into the housing first cools a housing circumferential wall surrounding the circumference of the coil, then cools the interface plate, and finally cools the coil before being discharged from a center portion of the housing. Thus, when reaching the interface plate, the air is already warmed and, therefore, this cooling technique cannot achieve the original purpose of cooling the interface plate brought closest to the patient. Additionally, since a portion of the air sucked into the housing may immediately be discharged outside by the fan without cooling the interface plate or without cooling the coil, this cooling technique has a problem of inability to achieve sufficient cooling efficiency.